1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member having a photosensitive layer in which a disazo pigment having a specific structure is present. The present invention also pertains to a process cartridge and an electrophotographic apparatus which employ such an electrophotographic photosensitive member.
2. Description of the Related Art
Electrophotographic photosensitive members employing organic photoconductive substances have advantages in that productivity is extremely high, that they are relatively inexpensive, and that color sensitivity thereof can be desirably controlled by adequately selecting the pigment or dye used. Therefore, research has heretofore been conducted on electrophotographic photosensitive members. The function separation type photosensitive member has been developed in which a charge generating layer containing an organic photoconductive substance, such as an organic photoconductive dye or pigment, and a charge transporting layer containing a charge transporting substance, such as a photoconductive polymer or a low-molecular organic photoconductive substance, are disposed as a laminate. Accordingly, the sensitivity and durability of the conventional organic photoelectric photosensitive members have thus been improved greatly.
Among organic photoconductive substances, azo pigments in general exhibit excellent photoconductivity. Furthermore, compounds exhibiting desired characteristics can be produced relatively easily by combining amine components with coupler components. Therefore, various types of compounds have heretofore been proposed in, for example, Japanese Patent Laid-Open Nos. Sho 54-22834, Sho 58-177955, Sho 58-194035, Sho 61-215556, Sho 61-241763, Sho 63-17456, Sho 63-259572 and Sho 63-259670.
In recent years, there have been demands for a higher image quality and a higher durability. To meet these demands, electrophotographic photosensitive members having higher sensitivity and exhibiting more excellent electrophotographic characteristics when used repetitively have been desired.